The number of implantable medical devices has dramatically increased in the field of medicine. Over the last decade, the use of stents, drug eluting stents, pacemakers, defibrillators, ventricular assist devices, glucose infusion pumps and neurostimulators has increased many folds. Some of the above enumerated examples, as well as a number of other implantable and/or non-implantable medical devices, are active devices that require power sources for operation.
The conventional power sources or batteries that are utilized in conjunction with implantable or non-implantable medical devices typically have stringent specifications imposed upon them relative to their physical size and performance. In older generation power sources, batteries that were designed for implantable medical devices were larger batteries, as compared to today's miniature batteries, and with a relatively short useful life. However, with the advent of miniature implantable medical devices for such diverse applications as drug delivery, glucose sensing and monitoring, and neurostimulation, batteries are required that are capable of providing useful power and occupying ever smaller volumes. In addition to small size, a battery that is to be implanted should preferably include a useful life, insignificant self-discharge rates, a high reliability over a long time period, and compatibility with a patient's internal body chemistry. In other words, it should be as biocompatible as possible. Biocompatible coatings and/or encapsulates well known in the art may be utilized to meet this need.
Implantable devices require power source(s) for their functional operation. For example, pacemakers have been widely used to stimulate heart muscles; and lithium batteries within the pacemakers are used to provide power to the pacemaker. Emerging technologies, such as MEMS (MicroElectroMechanical Systems), promise to improve the quality of life for patients that suffer from chronicle diseases. Implantable sensors made by MEMS technology have the advantages of low-cost, small-in-size, easy integration with the controlling integrated circuits (ICs) and low power consumption. However, the size of conventional lithium batteries is large compared to the MEMS-based sensors and post-processing will often be needed to integrate the battery with the sensors.
In the light of the aforementioned discussion, there exists a need of an implantable, self-rechargeable, bio-fueling micro battery that is useable for powering implanted medical devices. The power source of the micro-batteries of the present invention has many applications, such as monitoring and burning excess glucose in the blood. This is especially important for pill and insulin dependent diabetics who rely upon an external device for monitoring their blood sugar levels.